Apparatus for telephone-switchboards.



RHENTEDl 00T. 18, 1904.

` E. R. MGBEBTY.

APPARATUS PoR TELEPHONE SWITGHBOARDS.

APPLICATION FILED DBG. 26, 1899.

NO MODEL.

y" Inl-M /alzesges:

UNITED STATES Patented october 1s, 1904.

PATENT OFFICE.vv

FRANK R. McBERTY, OF EVANSTON, ILLINOIS, ASSIGNOR TO THE WESTERN ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

APPARATUSl Fo|=xv TELEPHONE-SWITCHBOARDS.

SPECIFICATION forming part of Letters Patent No. 772,896, dated October 18, 1904.

'n Application led December 26,1899. Serial No.' M1576. (No model.)

T @ZZ whom t may crm/cern.-

Beit known that I, FRANK R. MCBERTY, a citizen of the United States, residing at Evanston, in thecounty of Cook and State of .Illi- 5 nois, have invented a certain new and useful Improvement in 'Apparatus for Telephone' line a signaling device which may be actuated or displayed by means controlled at the corresponding substation and to substitute for this line-signal when connection is made with .2O the line a supervisory or clearing-out signal which also may be controlled from the substation, the line-signal being meantime inoperative. It will be understood that in some switchboards-in those of the multiple type,

for eXarnple--the connection with a line may 'be made at a point distant from the line-signal, in which case the supervisory signal furnishes the subscriberwith means of signaling to the operator in charge of the connection.

This invention applies to such signals; and it consists in an arrangement of circuits and apparatus for eiacing or rendering inoperative the line-signal when connection is made with the line, for substituting vtherefor a super- Visory signal, and for. bringing the latter signal under the control of the same relay which normallydetermines the excitement of the line-signal.

The novel feature of the invention consists.

in a local circuit including a battery, a subsidiary signal, and switch-contacts controlling the continuity-of the circuit, a shunt-circuitA v`tion for use.

by an electromagnet which receives current,

and thus becomes excited while the line is in use. The shunt about the line-signal and that 5o about the switchare closed through registering contact parts in the spring-jack and connecting-plug when connection is made with the line.- In this system of circuits the linesignal becomes displayed to indicate a call-' when the relay closes its switch-contacts as the substation apparatus is brought into posi- That signal is short-circuited, and thus effaced, when connection is made with theline, and the supervisorysignal is 6o displayed when the relay permits its switchcontacts toseparate, thus opening the shunt about it, presumably when the substation-telephone is no longer in use. When the supervisory signal is associated with the connecting plug and cord usuallyemployed in telephone-switchboards for uniting lines, it is preferable to include-in the circuit through the supervisory lamp the switch-contacts of Va plug-switch by which the circuit shall be 7o closed only during the use of the plugs in a connection. By this device waste of energy is avoided.

The invention is represented in the accoml panying drawings. 75

Of the drawings, Figure 1 is a diagram ofthe circuits of the invention separate from the other apparatus and circuits of the switchboard. Fig. 2 shows the circuits of the switchboard complete as far as an understanding oi' 8O the application and use oi' the invention require in connection with two telephone-lines extending to telephone-s'ubstations.

The circuit of the invention (seen ,in Fig. 1)

is a local circuit l 2, which is represented as a grounded circuit, including abattery a, and divided into' two parallel branches 3 and 4.

In one of these branches, 3, are a lamp b, a pair of switch-contacts c c', and ypreferably a resistance-coil Zin the order of naming. In 9o the other branch, 4, are aXresistance-coil @and av lamp f. Frorna point of conductor 3 between the lamp and the switch-contacts al conductor 5 is led to a point on wire 4C intermediate ot' the resistance-coil and the lamp.

This conductor is normally interrupted in contact-pieces f/ t. The coils (Z and c should be of low resistance. Each may have a resistance equal to about two-thirds of that of a lamp. Then the switch-contacts c c are closed together, the lamp b becomes lighted by the current in wire 3. Then if the conductor 5 be closed by bringing together the parts g and /2/ the lamps and f will be extinguished, being shunted bythe coils c and CZ, respectively. Then if the switch-contacts c c be .separated the lamp f will be lighted because ot' the breaking of the shunt aboutit. If desired, the waste of current when the lamps are shunted may be diminished by including in the circuit next each lamp a small additional resistance. The relations of the resistances in the different portions of the circuit may be adjusted to suit varying requirements or conditions. I will now describe the application of this circuit and apparatus to the well-known mechanism of a telephoneswitchboard to effect the objects announced in the foregoing general statement.

Each substation, as station I, is provided with` telephones /c t, a call-bell X22, a condenser IB in circuit with the bell, and al telephone-switch It* for closing the line-circuit through the telephone instruments. This apparatus is connected by line-wires G T with spring-jacks or terminal sockets and Z/ in a switchboard at a central station, the line lconductors being led iinally, the former through a relay m and the latter through an impedance-coil a, to earth. A battery 0 is interposed in the common earth branch ot' the line conductors 6 of the different lines. The usual plugs p and p', with their connecting plug-circuit 8 9, are furnished in the switchboard for uniting lines by means or' their spring-jacks. A condenser is included in each plug-circuit to maintain the independence of operation of the relays of two united lines. The usual listeningI and ringing key g is provided for connecting the operator-s telephone r or the generator s ot' calling-current with the plug-circuit. In associating the circuit or' Fig. t with this organization the lamp L is placed near a spring-jack of the line and serves as the subsidiary line-signal. The contact-points of relay m are utilized as the switch-contacts c c. The lamp f operates as a supervisory signal and is located near the plug p. The severed portions of conductor 5 terminate in the contact-piece fj of the plug p and in the contact-rings /L ot' the spring-jacks Z and Z. A plug-switch z5 is placed in the resting-socket of the plug, and its switch-contacts are interposed in conductor 4L to prevent the flow of current through the lamp f except while the plugs are in use.

It will be understood that the conductor 3 of the local circuit, with its included line-lamp and switch-contacts, is provided for each line,

while a conductor 4, with the supervisory signal, is associated with each connectingplug.

\Vliile1V have for convenience shown the local and line batteries l n as separate batteries, it will be understood, ol course, that in practice these may be one and the same battery.

In this system the removal ot the substationtelephone from its switch-as, for example, at station l---causes the corresponding relay to attract its armature and close the branch il which it controls. The line-lamp /1 is thus lighted. lts illumination constitutes a callsignal to the operator, who responds by inserting a plug 7) into spring-jack ol' the calling-line. Thisact brings her telephone 1' into connection with the line (the key l] having been placed in proper position) and permits her to receive the subscribers order tor the connection required. The lifting ol the plug from its socket allows the plug-switch to close the break in wire 4 ot' the local signalcircuit. The insertion of the plugin the spring-jack completes conductor 5 of the local circuit through the sleeve of the plug and the thimble ot' the spring-jack, and thus eti'ects the extinction ol the line-laml.` Supervisory lamp f also remains dark, being shunted by the closed switch-contacts c el ot: relay m. After testing the line called lor by appb'ingl the tip of the other plug, p, of the pair to the test ring or thimblc /t of the spring-jmfk /"'l ot' the line the operator inserts the latter plug into the spring-jack tested and operates the key q to ring the bell at the station ll. The removal of the plug p' from its socket ell'ects the completion of branch #t oi' the corresponding local circuit. The insertion of the plug in the spring-jack l closes the break in conductor 5. Hence the supervisory lamp associated with that plug becomes lighted, since the shunt-circuit about it is not vet closed at the line-relay and the line-lamp /f' ot` line to station Il is shunted or short-circuited. Then the subscriber at station Il, responding to the call, removes his telephone lrom its switch-hook, the line-relay m. ol that line becomes magnetizcd and closes the break in conductor 3 oi that line. The supervisory lamp oi plug` y1 is thus deprived ol current. lts extinction is a notilication to the operator that the called subscriber has answered. Thilo the subscribers continue in conversation both su pervisory signals remain dark. Yt'hen either replaces his telephone on its switch, the correspondingsupervisory lamp becomes lighted, and when linally both return their telephones to their normal positions both supervisory lamps are lighted. This last condition may be accepted by the attendant as an indication that conversation is completed and the lines may be disconnected.

Having thus described my invention` l claim as new and desire to secure by Letters Paten t l. 1n combination with a signaling-circnit,

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a line-signal and switch-contacts in series therewith controlling the circuit, a shunt-circuit for the line-signal not embracing said switch-contacts, an independent shunt around the switch-contacts not embracing said linesignal, and a supervisory signal in said independent shunt-circuit, and a switch adapted to close both said shunts, whereby in closing said switch the control of the switch-contacts over the line-signal is destroyed and the supervisory signal lis brought under their control instead. v u

2.` In a supervising-circuit for telephonelines, the combination with a signaling-circuit,

. having a relay responsive to currents in the' a line-signal therein and switch-contacts serially in the circuit with said line-signal, said' switch-contacts being controlled from the telephone-substation, a shunt for'theline-signal not embracing said switch-contacts, an independent shunt around the switch-contacts not embracing said line-signal, a supervisory signal in said last-mentioned shunt, a spring-jack for the Vline and a plug and plug-circuit to make connection therewith, and switch-contacts closed in inserting the plug in the springjack, adapted tolcomplete both said shunts, whereby prior to connection with the line the line-signal is controlled by vthe switch-contacts, but after connection with the line the and the line-signal in one of said branches to shunt the line-signal and tol bring the supervisory signal into shunt oi' therelay'contacts, substantially as described.

4. The combination with a telephone-line line, a spring-jack of the line and a plug and plug-circuit for making connection withthe line, of a subsidiary signaling-circuit including a source of current and divided into two parallel branches, the contacts of said relay being included in one of said branches, a linesignal permanently associated with the line in the same branch, a resistance-coil and a supervisorysignal associated with the plugin the other branch, and a conductor normally open at registering contacts of the connectingplug and spring-jack adapted to imite the two branches from points intermediate of the line signal and the relay-contacts in one branch,

and of the resistance-coil `and the supervisory signal in the other branch,and thereby to shunt the line-signal and bring the supervisory signal under the control of the relay when kconnection is made with the line, substantially as described.

5. The combination with acircuit 3 including serially1 a source of current, a line-signal and switch-contacts controlling the continuity of said circuit, of a conductor 4in parallel with the portion of said circuit including the line-signal and switch-contacts, a supervisory signal in said conductor, a cross-conductor adapted to be established from the conductor 8, between the line-signal and the switch-contacts, to the conductor 4 between the supervisory signal andthe source ofV current, and

means for connecting said cross-conductor, asv described.

6. The combination with a telephone-line including a relay responsive to currents inthe l line, and a subsidiary signal-circuit 3 including serially a source of current with a linesignal and switch-contacts of said relay, of'a conductor 4 in parallel with the portion oi' said circuit including the line-signal and switchcontacts, a supervisory signal in said conductor, a crosseconductor 5 adapted to be established from the conductor 3 between the line-signal and the switch-contacts, tothe conductor 4 between the .supervisory signal `and the source of current, and switch-contacts controlling the continuity of the conductor 4 and controlling the connection of the crossconductor as described, established in making connection with the telephone, whereby connection with the line brings the supervisory signal under the control of the line-relay and takes the line-signalout of the control of said relay, substantially asdescribed.

In witness whereof I hereunto subscribe my name this lst day of December, A. D. 1899.

FRANK R. MCBERTY. Witnesses:

GEORGE P. BARTON, y. P. W.` SKINKLE.

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